Where can one buy a good boar's hair spoke brush? According to properautocare.com:
"First, a lot of what's being sold as "boar's hair" isn't. It's horse hair that has been artificially stiffened with nylon or polyester. That wouldn't matter if you were scrubbing your dog but if you're washing your collector or exotic car, it can put washing swirls in the finish. You see, the advantage of real boar's hair is that it's the only natural hair that doesn't go limp when it's wet. It's naturally thick and sturdy. When wet, boar's hair holds an abundance of water. As a brush, boar's hair delivers mounds of soapy water with a bristle strong enough to scrub the surface yet soft as, well, hair. Real boar's hair will not scratch clear coat finishes or remove top wax or sealant coatings. It's truly unique.
The second little secret within the brush industry is that most boar's hair brushes, even the ones with real boar's hair, fall apart. The reason for this is the way most brushes are made. Bundles of boar's hair are "compression-fit" into holes, usually in a plastic block. As the brush ages, normal bristle movement causes the hair bundles to loosen and fall out, often dozens at a time."